[ObjC ARC] Converts ios/chrome/browser/ui/first_run:unit_tests to ARC.

ios/chrome/browser/ui/first_run/first_run_util_unittest.mm

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <UIKit/UIKit.h>
 
-#include "base/mac/scoped_nsobject.h"
 #include "ios/chrome/browser/ui/first_run/first_run_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 TEST(UICommonTest, TestFixOrphanWord) {
   NSString* englishString =
       @"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec tempus"
        " dignissim congue. Morbi pulvinar vitae purus at mollis. Sed laoreet "
        "euismod neque, eget laoreet nisi porttitor sed.";
   NSString* englishStringWithOrphan =
       @"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec tempus"
        " dignissim congue. Morbi pulvinar vitae purus at mollis. Sed laoreet "
        "euismod neque, eget laoreet nisi.";
   // TODO(crbug.com/675342): clang_format does a poor job here. Remove when
   // fixed in clang_format.
   // clang-format off
   NSString* chineseString =
       @"那只敏捷的棕色狐狸跃过那只懒狗。那只敏捷的棕色狐狸跃过那只懒狗。"
        "那只敏捷的棕色狐狸跃过那只懒狗。那只敏捷的棕色狐狸跃过那只懒狗。"
        "那只敏捷的棕色狐狸跃过那只懒狗。那只敏捷的棕色狐狸跃过那只懒狗。";
   NSString* chineseStringWithOrphan =
       @"那只敏捷的棕色狐狸跃过那只懒狗。那只敏捷的棕色狐狸跃过那只懒狗。"
        "那只敏捷的棕色狐狸跃过那只懒狗。快速狐狸";
   // clang-format on
 
-  base::scoped_nsobject<UILabel> label(
-      [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 300, 500)]);
+  UILabel* label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 300, 500)];
   [label setText:englishString];
   ios_internal::FixOrphanWord(label);
   NSRange range = [[label text] rangeOfString:@"\n"];
   // Check that the label's text does not contain a newline.
   EXPECT_EQ(NSNotFound, static_cast<NSInteger>(range.location));
 
   [label setText:englishStringWithOrphan];
   ios_internal::FixOrphanWord(label);
   range = [[label text] rangeOfString:@"\n"];
   // Check that the label's text contains a newline.
@@ skipping 15 matching lines @@
   range = [[label text] rangeOfString:@"\n"];
   // Check that the label's text contains a newline.
   ASSERT_NE(NSNotFound, static_cast<NSInteger>(range.location));
 
   // Check the words after the newline.
   wordsAfterNewline =
       [[label text] substringFromIndex:(range.location + range.length)];
   EXPECT_TRUE([@"快速狐狸" isEqualToString:wordsAfterNewline]);
 }
 }